A respawned backend re-mints runtime ids, so a pre-reconnect busy state
never receives its terminal busy:false publish and its session stayed in
$workingSessionIds forever - the sidebar running arc and agents-panel
'running' chrome lied for hours after the turn ended (the stale-flag
half of #53902/#73082; the CSS cost half landed in #91383).
reconcileBusyStatesOnReconnect() downgrades busy/awaitingResponse states
through publishSessionState (watchdogs disarm, stall hints drop, settle/
unread bookkeeping stays consistent), scoped by event-source: the primary
reconnect touches only scope-less runtimes, a secondary (registry)
reconnect touches only its own connection's. needsInput survives - a
blocking prompt is the user's to answer. A genuinely live turn re-asserts
busy on its next post-reconnect event, so the worst case is one arc blink.
Regression tests proven by sabotage run (neutered reconcile -> 5/6 fail).
Teknium
4f64807f5d